Electric switch.



T. E. BARNUM.

ELECTRIC SWITCH.

ABPLIOATIOR FILED mm: 20, 1910.

Patented May 12, 1914.

UNITED sTATEs PAT ENT OFFICE.

THOMAS E. BARNUM, or MILWAUKEE, 'e'ssrono'n TO THE CUTLER- HAMMER MFG.00., 0E MILWAUKEE, WISCONSIN, A conrona'rron OF WISCONSIN.

ELECTRIC swnrcm T 0 all whom it may concern Be it known that I, THOMASE..BA RNUM, a citizen of the United States,.resid1ng at Milwaukee in thecounty of Milwaukee and ranged to make a sliding contact therewith.

lari structure illustrated. I

. My invention is One object of my invention is to provide a simple butsubstantial'contact, which will insure a good electrical connection withits cooperating movable. contact, and which will prove very durable inservice.

A further object of my invention is to provide a contact which maybereadily removed for repairs and-which may be as easily replaced.

Various other objects and advantages of my invention will hereinafter beset forth.

.Forrthe purpose of more fully disclosing the nature .and advantages ofmy invention, I; shall describe the embodiment thereof illustrated inthe accompanying drawing. It should .be understood,lho.wever-, that my;invention is capable of various modifications and therefore, is notlimited to the particu- Inthe accompanyingv drawing, Figure 1 is a sideelevation of a switch embodyingmy' invent-ion in its preferred form, andFig. 2.

is ,a perspective view of the stationary contact-finger. ,7 particularlyapplicable to. drum controllers, and therefore, I haveshown my inventionused in such a connection, in the accompanying drawing. {It should beunderstood, however, that contacts;

embodying my invention may be used for various other kinds of switches.It being: unnecessary to show a complete controller in order to disclosemy invention, I have merely shown one of the drum segments and; itscooperating contact finger. I have shown .-a shaft 1 having a contactsegmentj mount.

ed thereon, and arranged to engage a ,cpu tact finger 3. The contactfinger 3 comprises an elongated bar of suitable conducting ma-Specification of letters Yatent. P t nt May '12, 1 Application filedJune 29, 916.

Serial No. 669,593.

terial, such as brass. In order to reduce the weight of the contactfinger and yet give. the same the desired amount of rigidity, I h. vechanneled out a portion on the to the eof leaving longitudinallyextendin fliinges, or ribs on opposite sides t ereof. Of course, inpractice the contact, finger might be formed in other ways. Forinstance, it .might be formed of sheet metal reinforced by beads, orflanges to give the desired rigidity thereto. The active end 5. of thecontact finger is, referably slightly enlar ed, and has securec to theunder side thereo or formed-integrally therewith, a suitable contactportion (3 preferably curved to facilitate the engagement thereof withthe contact segment 2.. At its rear end, the contact finger is providedwith a transverse downardly extendin lug 7- having a substantlallysemi-cylindrical extremity.

In "drum cont-rollers it is customary to provide an insulating base,such as the base 9 for supporting the contact fingers. This hase may beformed of wood, or any other desired material. To this base, I secure byany suitable means, such as screws 10, a support 11 for the contactfinger. The support 1],, as illustrated, is provided at its rear endwith-a portion 12 having binding posts 13 and 14 thereon for making thedesired electric connections with the contact finger. The contactsupport, or bearing block, may be formed of any suitable material, butin practice .I prefer. to form the same ofbrass... Extendingtransversely of the s11 pport,-or bearing block, 11 is a groove 15.adapted to receive and form a bearing for thelng 7 .o:;th e;contactfinger. The groove 15 1s preferably vmade flaring, but havingthe.bottom thereof curved correspondlngly to the curvature of the lug 7..This,-arrangementin e'fiect forms a trunnion bearing. for: :thecontactfingenj u For maintaining the lug Z of thecontact finger in ,thegroove 15, and yet permittmg the desired movement of the contact finger,.L-have provided a tension device -16.-. This device comprisesa "pin .17secured tothe support 11 and projecting througha slot 18 in;the;contact=,finger,. and. having mount ed thereon, a conical spring 18interposed lie ween .g le contactfinger. apda collar 19 ,h' d on e outerend of the rod 17 by a removable pin 20. I

For limiting the movement of the cong oseaea tact finger under theinfluence of the spring 18, I have provided on the support 11 aprojection 21 arranged to be engaged by an adjustable set screw 22carried by said contact finger. With this arrangement the retent-ion ofthe contact finger, in engagement with its supporting base is insuredand the movement of said finger under the influence of the spring 18 maybe limited as desired, While the resiliency of the spring will allowsaid finger to yield to the movable contact, and yet firmly hold thesame in engagement therewith.

As illustrated, the portion 24 of the rod 17 has a screw threadedengagement with the contact support, or bearing block, and might beadjusted therein to vary the pressure exerted by the spring upon thecontact finger. While the contact finger is in direct electricalengagement with the support 11, yet I prefer to further electricallyconnect said finger with said support by means of a flexible lead 25.

lVith the arrangement illustrated, when the contact segment is movedunder the con-.

tact finger it turns said contact finger in its bearing therebycompressing the spring 18. This compression of the spring obviouslytends to increase the pressure on the contact finger and hence holdssaid finger in firm engagement with the segment. When the segment ismoved out of engagement with the contact finger, the contact fingermoves under the influence .of the spring 18 until.

the set screw 22 thereof engages the lug 21 in which position it isarrested and remains until the segment is again moved into engagementtherewith. l/Vhen desired to remove the contact finger, it is merelynecessary to disconnect the lead therefrom, or from the base 11, thenremove the pin 20 from the rod 17 and then lift the contactfinger out ofplace. On the other hand, in replacing the contact finger it is onlynecessary to place the same on the rod 17, then place the spring 18 andcollar 19 on the rod,

insert the pin 20 and, if necessary, shift the contact finger until thelug 7 thereof finds its place in the groove 15. No further attention isrequired except in connecting the contact finger to the lead 25. Themeans for holding the contact finger in place, and the adjusting means,are both on the-exposed side of the switch and, hence, are readilyaccessible when it"is desired to remove, or adjust the contact finger.

Having thus described my invention. what I'claim as new and desire tosecure Letters Patent, is:

1. In an electric switch, in combination,

a support, a contact finger having at one end an open pivotal bearing onsaid support and having at its other end a contact,

apin mounted on said support and extendthrough said contact. fingerintermediate its ends, and a coil spring surrounding said pin andbearing upon said contact finger to hold the latter in engagement withsaid support and permit movementof said contact, said support having anextension to limit the movenzent of said contact finger in onedirection.

3. In an electric switch, in combination, a

support, a contact finger having at one end an open pivotal bearing onsaid support and having at its other end a contact piece, a pin mountedon said support and extending through said contact finger intermediateits ends, a coil spring surrounding said pin and pressing upon saidcontact finger'to hold the latter in engagement with said support, andadjust-able means on said contact finger to limit the movement of thesame in one direction.

4. In an electric switch, in combination, a support having a groovetherein, aconta'ct finger having at one end a lug resting in said grooveand having at its other end a contact piece, a pin mounted on saidsupport and extending through said contact finger intermediate its ends,a collar on said pin, a coil spring surrounding said pin between saidcollar and said contact finger to hold the latter in engagement withsaid Support, adjustable means carried by said contact finger to'limitthe movement thereof in one direction and a flexible conductor betweensaid support and said contact finger, said flexible conductor, saidspring and said adjustable means being accessible from the exposed sideof said contact finger.

In witness whereof, I have hereunto subscribed my name" in the presenceof two witnesses.

THOMAS E. BARNUM.

- Witnesses:

FRANK H. HUBBARD,

GEORGE HAYNES.

